[PATCH v4 01/10] platform/x86/intel/pmt: fix a crashlog NULL pointer access

[Michael J. Ruhl]

Usage of the intel_pmt_read() for binary sysfs, requires a pcidev.  The
current use of the endpoint value is only valid for telemetry endpoint
usage.

Without the ep, the crashlog usage causes the following NULL pointer
exception:

BUG: kernel NULL pointer dereference, address: 0000000000000000
Oops: Oops: 0000 [#1] SMP NOPTI
RIP: 0010:intel_pmt_read+0x3b/0x70 [pmt_class]
Code:
Call Trace:
 <TASK>
 ? sysfs_kf_bin_read+0xc0/0xe0
 kernfs_fop_read_iter+0xac/0x1a0
 vfs_read+0x26d/0x350
 ksys_read+0x6b/0xe0
 __x64_sys_read+0x1d/0x30
 x64_sys_call+0x1bc8/0x1d70
 do_syscall_64+0x6d/0x110

Augment the inte_pmt_entry to include the pcidev to allow for access to
the pcidev and avoid the NULL pointer exception.

Fixes: 416eeb2e1fc7 ("platform/x86/intel/pmt: telemetry: Export API to read telemetry")
Cc: <stable at vger.kernel.org>
Signed-off-by: Michael J. Ruhl <michael.j.ruhl at intel.com>
---
 drivers/platform/x86/intel/pmt/class.c | 3 ++-
 drivers/platform/x86/intel/pmt/class.h | 1 +
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/platform/x86/intel/pmt/class.c b/drivers/platform/x86/intel/pmt/class.c
index 7233b654bbad..d046e8752173 100644
--- a/drivers/platform/x86/intel/pmt/class.c
+++ b/drivers/platform/x86/intel/pmt/class.c
@@ -97,7 +97,7 @@ intel_pmt_read(struct file *filp, struct kobject *kobj,
 	if (count > entry->size - off)
 		count = entry->size - off;
 
-	count = pmt_telem_read_mmio(entry->ep->pcidev, entry->cb, entry->header.guid, buf,
+	count = pmt_telem_read_mmio(entry->pcidev, entry->cb, entry->header.guid, buf,
 				    entry->base, off, count);
 
 	return count;
@@ -252,6 +252,7 @@ static int intel_pmt_populate_entry(struct intel_pmt_entry *entry,
 		return -EINVAL;
 	}
 
+	entry->pcidev = pci_dev;
 	entry->guid = header->guid;
 	entry->size = header->size;
 	entry->cb = ivdev->priv_data;
diff --git a/drivers/platform/x86/intel/pmt/class.h b/drivers/platform/x86/intel/pmt/class.h
index b2006d57779d..f6ce80c4e051 100644
--- a/drivers/platform/x86/intel/pmt/class.h
+++ b/drivers/platform/x86/intel/pmt/class.h
@@ -39,6 +39,7 @@ struct intel_pmt_header {
 
 struct intel_pmt_entry {
 	struct telem_endpoint	*ep;
+	struct pci_dev		*pcidev;
 	struct intel_pmt_header	header;
 	struct bin_attribute	pmt_bin_attr;
 	struct kobject		*kobj;
-- 
2.49.0